Rust preventive compositions



Patented Mar. 1 6, 1954 RUSTPREVENTIVE COMPOSITIONS Jones I-. .Wasson,Union,

South Orange,

and Douglas L. Bonham, N. J., assignors to Standard Oil DevelopmentCompany, a corporation of Delaware No Drawing; Appl June 1948 Serial No.31,404

2 Claims. (01. 252 s3.4

The present invention'relates to rust preventivecompositionsand-particularly to compositions which are useful inlubricating oils, especially mineral base lubricating oils and the like,to enhance their rust preventive characteristics. The invention isconcerned also with an inhibited oil 'as a new composition of matter.

Under certain conditions, particularly conditions of elevatedtemperature and high humidity, the problem 'ofpreventing rust,particularly of polished steel surfacesor highly machined surfaces, is avery serious one. Numerouscompositions have been prepared in recentyears in attempts to meet this problem and. to provide slushing oils,lubricating oils, and the like, which give good protection against rustto steel and iron surfaces. Some of these have met with fairly goodsuccess but further improvements still appear to be in urgent need.

The present invention is based 'upon the discovery that certain esters,especially those esters which are predominantly mono-esters ofpolyglycerol have unusual and unexpected rust inhibiting properties,especially when used in liquid lubricating oils, slushing oils and thelike. It has been suggested in the United States'patent to Hodson, No;2,345,199 that certain esters of glycerol may be used in lubricatingcompositions. The present invention is based on the discovery of a verymaterial and striking improvement in the rust inhibiting qualities ofthe polyglycerol esters as distinguished from the simple monoglycerolesters.

In addition to rust preventing characteristics, the present invention isconcerned with the im provement of extreme "pressure or load carryingcharacteristics of mineral lubricating oils. The partial esters involvedin the present invention impart outstanding rust preventive propertiesand at the same time improve materially the load carrying propertiesor'mmem lubricating oils evenin very low percentages, for example inproportions of a's-little (as 0.1 and up to by weight, based on thetotal lubricant. These materials may be used in transformer oils, inordinary lubricating oils, in slushing compounds which also may, ifdesired, contain otheradditives such as petroleum sulfonates, "degrasand the like, and, alsofin greases... They'n ay also" be reacted" withcompounds which incorporate therein sulfur, phosphorus or other loadcarrying agents to provideextreme pressure lu bricants. Thephosphoriz'ed or sulfurized compounds, as well as the simplepolyglycerol esters, may be used in lubricating greases as "well as inslushing oils and liquid lubricants;

A typical starting material for carrying out the present inventionconsists of polyglycerol prepared by heating glycerin with or without acatalyst. Catalysts such as iodine, hydrochloric acid, or potassiumhydroxide may be employed for more rapid polymerization if desired, butare not absolutely necessary. By heating the glycerin, with or without acatalyst, to a temperature of 225-250 F. for a suitable period; anappreciable increase in molecular weight results. The heating timemayvary considerably depending upon the catalyst used, etc. It has beenfound that a heating period of 15'to- 48 hours may ordinarily berequired. Under such con ditions, the viscosity of the treated glycerinincreases from an initial value of 550 S. S. U. at F. to about 1070 S.S. U. at the same-temperature. The product having aviscosity of 1070 S.S. U. appears to be predominantly the dimer of glycerin although'higherpolymers are probably present in minor quantities. I

A polyglycerol, prepared as indicated "above, was esterified to producea product consisting predominantly ofthe monoester by reacting thepolymer with the calculated amount of oleic acid for a period of about 4hours'at 380 F. As'a catalyst 0.2% by weight, based on the reactantmaterials, of tin tetrachlorideYSnCh) was used. The esterified productwas finished by filtering it through-a thin layer of oil-filtering clay.It might also be'purified by water washing' 'if desired. Theproduct-prepared as above described had a neutralization number of 1.4and a saponi fication number of'171. To determine the rustinhibitingproperties 01" these polymers, steel panels were'immersed inthe oil blends described below and then suspended in a standard AN-H-31humidity cabinet at a temperature of'120 F. w

Under these conditions; panels coated witha transiormeroilhavingafviscosity of 58 SflU. at 100 Ff'had a humidity cabinet life(hours to incipient rusting) of .approximatelyone-"half hour.

The addition o'f"'3'% by" weight of the simple glycerol mono-oleate tothe same oil resulted in a humidity cabinet life of 24 hours. However,when 3% by weight of polyglycerol mono-oleate was added to thetransformer oil, the humidity cabinet life was increased to 240 hours.

Similarly, panels coated with an aviation oil having a viscosity of 120S. S. U. at 210 F. had a humidity cabinet life of approximately onehour, but on the addition of 3% by weight of polyglycerol mono-oleatethe humidity cabinet life was extended to 280 hours.

TABLE 1 ANH-31 humidity cabinet results n Hours for Mineral Oil RustPreventive Rust To Develop Transformer OiL... None V Do 3% GlycerolMono-oleate 24 3% Polyglycerol l\C[ono-oleatc 240 l None l. 3%Polyglycerol M one-010mm... 230

A further investigation of the rust inhibiting properties of thepolyglycerol partial esters was conducted using a combination internalcombustion engine-humidity cabinet test as follows.

A single cylinder air-cooled engine of 4.5 hp.,

operating at 2000 R. P. M. manufactured by the Wisconsin MotorCorporation, was operated on leaded gasoline and lubricated with the oilblend under investigation. Subsequent to being used in the engine withthe oils described below, the i.

cylinder-cylinder liner assemblies were stored in a humidity cabinetoperating at a temperature varying between 70 and 90 F. during each 24hour period and with relative humidity varying between 50% and 95%during the same period. After five days of storage in the cabinet underthe conditions described, the amount of rusting of the cylinder liner ineach case was noted in terms of the percentage of the entire surfacewhich had become rusted. When an aviation oil of 120 S. S. U. viscosityat 210 F. was used as the lubricant in the above procedure, 30% rust wasobserved after 5 days of storage. However, the same base oil containing1% by weight of polyglycerol mono-oleate resulted in only 6% of rustafter 5 days of storage.

In addition to having excellent rust preventive properties the partialesters of polyglycerol are good oiliness agents and improve the loadcarrying properties of mineral base lubricating oil. A transformer oilsubjected to the standard Almen extreme pressure test carried a weightof only 1 unit before failure. The same oil, including 2% by weight ofpolyglycerol mono-oleate, carried 6 weights before failure.

The prior art has shown that rust inhibiting compounds, such as slushingoils and the like, may be prepared by adding oil soluble petroleumsulfonates, degras and the like to mineral oils. For many uses suchcompounds are very satisfactory but under extreme conditions oftemperature and humidity they show early failure. Tests have nowdemonstrated that by the addition to such compositions of smallquantities of polyglycerol mono-oleate prepared as indicated above, theanti-rusting life was greatly extended. Table 2 shows the results ofAN-H-Bl humidity cabinet tests using a transformer oil base with variousquantities of sulfonates and polyglycerol mono-oleate.

TABLE 2 AN-H-31 humidity cabinet results The composition including about3% of polyglycerol mono-oleate and a small amount of sodium sulfonateproved highly satisfactory. The same was true with a compositionincluding only 1% of polyglycerol mono-oleate tog-ether with 2% sodiumsulfonate and 2% degras. Oil including only the sulfonate and degrasshowed a shorter effective life as a rust preventative.

It has been found that other materials may be used in lieu of thoselisted in Table l, for example, various metal salts of petroleumnaphthenates may be'used in conjunction with the partial esters ofpolyglycerol. Other conventional additives may also be included such asdetergents, fatty oils, antioxidants, viscosity index improvers, pourpoint depressants and the like.

In lieu of partial esters of polyglycerol and oleic acid, partial estersof polyglycerol with other organic acids either singly or in combinationmay be employed. Thus partial or mixed esters of polyglycerol withstearic acid, lauric acid, naphthenic acids, tall oil and the like maybe employed.

As indicated above, partial esters of the type described in theforegoing may be reacted with phosphorus compounds, phosphorus-sulfurcompounds and/or free sulfur to improve the load carrying properties oflubricants which contain such esters. Thus the partial esters ofpolyglycerol may be reacted with PCla, POCla, P255, P3S4, sulfur and thelike to introduce phosphorus, sulfur, chlorine or any two or more ofthese into the partial ester molecule. Esters so treated have theproperty of reacting with metal bearing surfaces at high temperatures toform therewith a highly effective load carrying film which preventsexcessive wear. Chemical reactions referred to may be indicated asfollows:

a. 3RCOO CHcCHOHCHzOCHzCHOHCHzOH P 0 C11;

(Diglyccryl mono-olcatc) (RC 0 O CHzCHOHOHzO CH2CHOHCHzO)3P=O 31101 I).411000 CHZCHOHCHBOCHZCHOHCHLYOH P 5 R represents an aliphatic radical ofa sufficient number of carbon atoms to give oil solubility.

The PgSa reaction product can also be reacted with metal oxides to formdetergent additives for oils.

From the foregoing it will be understood that a preferred composition isone which consists essentially of an oily base lubricant or lubricatingtype composition (oil or grease, etc.) containing a proper amount ofafatty acid ester of polyglycerol. For ordinary use, the proportions ofester to lubricant should be not less than 0.1 nor more than about byweight of the ester based on the finished composition. It is desirable,however, for some purposes, to market the ester-containing material as aconcentrate. Where this is done the composition ma contain as little as60% of the oil or lubricant and as much as 40% of the ester, with orwithout appropriate quantities of metal sulfonates, degras, and thelike. Where used, these latter ingredients may consttiute 0.1 to 10% byweight of the composition. In concentrates the proportions may behigher. The sulfonates, such as sodium or other alkali or alkaline earthmetal sulfonates may comprise as much as or more by weight.

In the examples above, reference has been made specifically to minerallubricating oil as the base material and such oil is ordinarilypreferred. Its viscosity may be as low as about and as high as 1000 S.S. U. at 210 F. It will be understood, however, that synthetic oils mayalso be used such as organic polymers and copolymers, esters and thelike. Hence in the claims, reference to the base lubricant includessynthetic materials as well as petroleum base or hydrocarbon base oilsand greases. By the expression base it is intended to includecompositions which comprise soaps, thickeners, viscosity indeximprovers, extreme pressure additives, oiliness agents, anti-oxidants,corrosion inhibitors, and the like. Materials such as sulfonates, degrasand the like which have been found suitable for use in slushing oils arealso included.

The fatty acid which is used to esterify the polyglycerol may containnot less than 10 nor more than about 24 carbon atoms and may besaturated or unsaturated, preferably the latter.

The preferred polyglycerol is the diglycerol as 4 previously suggested,but also suitable.

For preparing the polyglycerol, monomeric glycerin is preferably heatedto a temperature Within the range of 200-300 F. As indicated above, thereaction time required varies with temperature and when the specificpreferred range of 225250 F. is employed the reaction time required isof the order of 15 to 48 hours. For esterifying, a higher temperature isordinarily required, for example, 250-400 F., although a lowertemperature such as 210250 F. may be employed, especially if a Waterentraining agent such as toluene or naphtha is employed. Asesterification catalyst, SnClr is suitable, but other known catalystssuch as sulfuric acid, toluene sulfonic acid, aluminum chloride, boronfluoride and the like may also be used.

higher polymers are RCOOCI-IzCI-IOHCI-IzOCHzCI-IOHCI-IzOX where R is aradical having 10 to 24 carbon atoms and X is a radical containingactive phosphorus.

It will be understood by those skilled in the art that variousmodifications may be made in proportions, temperatures of reaction, theuse of catalysts, etc. as will be obvious.

What is claimed is:

1. A composition consisting essentially of hydrocarbon oil baselubricant containing 0.1 to 10% by weight of mono-oleate ester ofpolyglycerol which is predominantly diglycerol, said polyglycerol beingprepared by heating glycerin to a temperature within the range of about225 to 250 F. for a period of time sufficient to increase its viscositysubstantially, 0.1 to 10% of metal sulfonate, and 0 to 10% of degras.

2. A rust preventive composition consisting essentially of a mineralbase lubricating oil, about 1 to 3% by weight, based on the totalcomposition, of the monooleate ester of a polyglycerol which ispredominantly diglycerol produced by heating glycerin to a temperaturewithin the range of 225 F. to 250 F. for a period of between 15 and 48hours, and 1.5 to 2% of oil soluble sodium petroleum sulfonate.

JONES I. WASSON. DOUGLAS L. BONHAM.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,534,752 Watson Apr. 21, 1925 2,182,992 Lebo Dec. 12, 19392,242,260 Prutton May 20, 1941 2,334,239 Barnett Nov. 16, 1943 2,398,193Sharp Apr. 9, 1946 2,407,954 Fenske et a1 Sept. 17, 1946 2,441,587Musselman May 18, 1948 2,434,490 Duncan Jan. 13, 1948 2,479,424 SprouleAug. 16, 1949 2,481,372 Fuchs Sept. 6, 1949

1. A COMPOSITION CONSISTING ESSENTIALY OF HYDROCARBON OIL BASE LUBRICANTCONTAINING 0.1 TO 10% BY WEIGHT OF MONO-OLEATE ESTER OF POLYGLYCEROLWHICH IS PREDOMINANTLY DIGLYCEROL, SAID POLYGLYCEROL BEING PREPARED BYHEATING GLYCERIN TO A TEMPERATURE WITHIN THE RANGE OF ABOUT 225* TO 250*F. FOR A PERIOD OF TIME SUFFICIENT TO INCREASE ITS VISCOSITYSUBSTANTIALLY, 0.1 TO 10% OF METAL SULFONATE, AND 0 TO 10% OF DEGRAS.